How so? I mean, isn’t that the opposite of what they’re supposed to do?! I didn’t pursue electrical engineering heh, and have only a basic grasp of lead-acid, so curious.Funny you say that. While I was waiting for parts for the tranny and truck sat for a month without being driven. I put it on a battery tender two weeks in and I think it may have helped kill my battery and cause the weird electrical stuff I had going on.